The couple, David 56 and Louise, 49, claimed to home-school their children, and the faeces-littered living room included eight small desks, a chalkboard, alphabet and number signs stapled to the wall.

The family lived in the rural neighbourhood, south of Dallas with eight children from approximately 2000 to 2004 before they abandoned the property and moved to Perris in California.

There, last week, both were each charged with multiple counts of torture, child abuse, the abuse of dependent adults and false imprisonment relating to the children aged from two to 29. They pleaded not guilty to all counts and are being held in custody on $9 million bail each. (£6.5m)

David Turpin was also charged with one count of a lewd act on a child by force. If convicted, they face up to 94 years to life in prison.

Jose Medina told The Telegraph: “What happened in the city of Perris was tragic, and it was horrific. And I would like to try to do everything I can to ensure that it doesn’t happen again.”

The Turpins' 13 children, aged between two and 29, had all, except the eldest, been exclusively home-schooled - meaning that, under California law, there was no outside contact.

“One of the reasons this went undetected was because the parents could keep the children hidden from the public,” said Mr Medina. “So I’m looking at what the state can do, so that kids can no longer be kept in captivity.”Two million children in the US are home-schooled, representing three per cent of all American youngsters, according to the Mike Smith, president of the Home School Legal Defense Association (HSLDA). The trend began in the 1970s, he told The Telegraph, but has increased in recent years. By contrast, in the UK only 30,000 children were educated at home in the 2016/17 academic year, out of over eight million.